Numerous drugs, medications and other substances are inhaled into the lungs for rapid absorption in the blood stream and systemic delivery, or alternatively for therapeutic treatment locally. Inhaled drugs are typically either in aerosolized or powder form. In either case, the delivered agent should have a particle or droplet nuclei size that is 5 microns or less in order to reach the terminal ramifications of the respiratory tree.
Such small particles are, however, thermodynamically unstable due to their high surface area to volume ratio, which provides significant excess surface free energy and encourages particles to agglomerate. Agglomeration of the particles, and adherence of the particles to the internal surfaces of the inhaler, result in delivery of particles that are too large in size, delivery of a lower dose due to particles adhering to the interior surfaces of the inhaler, and poor flow and non-uniform dispersion resulting in the delivery of a varying dosage. In addition, as noted above, many dry-powder formulations employ larger excipient particles to promote flow properties of the drug. However, separation of the drug from the excipient, as well as the presence of agglomeration, can require additional inspiratory effort, which, again, can impact the stable dispersion of the powder within the air stream of the patient. Unstable dispersions may inhibit the drug from reaching its preferred deposit/destination site and can prematurely deposit undue amounts of the drug elsewhere.
Further, the hygroscopic nature of many dry-powder drugs may also require that the device be cleansed (and dried) at periodic intervals.
U.S. Patent Application Publication No. 2013/0042864, filed Oct. 3, 2012, which is hereby incorporated herein by reference in its entirety, describes a dry-powder inhaler including a casing having an air inlet located at a first terminus, a powder delivery port located at a second terminus and positioned distal to the air inlet, and an elongated assembly located within the interior of the casing. A first assembly terminus is located proximally to the air inlet, and a second assembly terminus is located proximally to the powder delivery port. The elongated assembly is fitted within the casing such that the assembly partially rotates within the casing about a single axis, and said elongated assembly comprises at least one compartment containing a dry-powder and located proximally to the second assembly terminus. The dry-powder compartment includes a porous structure encasing the dry-powder; whereby airflow through the device causes the assembly to partially rotate or pivot within the casing about a single axis, and dry-powder is thereby released from the compartment and becomes entrained in the airflow.
However, it is important to provide a single use (disposable) dry-powder inhalation device that facilitates the dispersion of active drug powder and delivers a consistent dose to the lung for respiratory disease treatment or the deep lung for systemic drug delivery. Many inhalation devices, such as described in U.S. Patent Application Publication No. 2013/0042864, require a mesh to be arranged over the dry-powder compartment and an additional film to be placed over the mesh in order to hermetically seal the compartment from air and prevent loss of the drug by movement or transport. Unfortunately, the process of filling the compartment, placing the mesh over the compartment and placing the film over the mesh is expensive and slow. Furthermore, the film is attached by glue or press, and must be pulled from over the cavity before use. However, pulling the film will twist the thin elongated assembly and disrupt its delicate rotating operation. Furthermore, developing an appropriate removable system and assembling it as an integrated part of the inhalation device is expensive and will require careful, complicated operating instructions.
Therefore, a need exists for improved disposable, single dose, dry-powder inhalation device that facilitates the dispersion of active drug powder and delivers a consistent dose to the lung, and that does not utilize mesh, cover film, glue or other means to seal the dry powder compartment.
In addition, a need exists for an improved single dose disposable dry-powder inhalation device that facilitates the dispersion of active drug powder and delivers a consistent dose to the lung the inhaler, but that does not require pushing, pulling or twisting of the inhalation device or of any of its components in order to withdraw the active drug powder from the dry-powder compartment.